Migraines are a pervasive problem. In particular, migraines may lower overall quality of life, including, but not limited to, quality of sleep. The neurobiology of sleep problems in patients with chronic pain share significant overlaps with those of insomnia suggesting another medical disorder that may benefit from the frontal hypothermia device. Among the most common causes of pain that disrupt sleep is headaches (50% of whom sleep disturbances trigger headaches and 71% of migraine sufferers have migraines that awaken them from sleep).
Sleep is essential for a person's health and wellbeing, yet millions of people do not get enough sleep and many suffer from lack of sleep. Surveys conducted by the U.S. National Science Foundation between 1999 and 2004 found that at least 40 million Americans suffer from over 70 different sleep disorders, and 60 percent of adults report having sleep problems a few nights a week or more. Most of those with these problems go undiagnosed and untreated. In addition, more than 40 percent of adults experience daytime sleepiness severe enough to interfere with their daily activities at least a few days each month, with 20 percent reporting problem sleepiness a few days a week or more. Furthermore, 69 percent of children experience one or more sleep problems a few nights or more during a week.
Insomnia is the most common sleep complaint across all stages of adulthood, and for millions of people, the problem is chronic. Many health and lifestyle factors can contribute to insomnia including stress, depression, medical illnesses, pain, medications, or specific sleeping disorders. There is great need for additional research to better define the nature of chronic insomnia.
Existing treatments of neurological and/or sleeping disorders, including insomnia, include the use of over the counter or prescription drugs and/or behavioral treatments. Prescription drugs are known to aid patients suffering from sleeping disorders, however, these drugs can be quite expensive and potentially addicting. Some medications even become less effective as use continues. Additionally, the prescriptions can have unwanted and harmful side effects.
Other techniques to treat sleeping disorders include a variety of behavioral measures including stimulus control therapy, sleep restriction therapy, relaxation training, cognitive therapy, and sleep hygiene education. While these measures have moderate effectiveness, they are costly, require significant time to implement and require highly trained clinicians to implement.
One treatment technique previously described addresses these issues by using non-invasive and localized or regional thermal stimuli to the brain that helps treat sleep disorders, including insomnia. Specifically, this method may help restore or mimic normal function in the cerebral cortex. The restoration of function in the cerebral cortex plays a significant role in sleep. At the molecular and neuronal levels, hypothesized functions of sleep include the restoration of brain energy metabolism through the replenishment of brain glycogen stores that are depleted during wakefulness and the downscaling of synapses that have been potentiated during waking brain function. A homeostatic sleep drive, or pressure for sleep, is known to build throughout the waking hours and then is discharged during sleep. At the electroencephalographic (EEG) level, this is measured by EEG spectral power in the delta (0.5-4 Hz) frequency band.
These sleep-related processes have some regional specificity for the prefrontal cortex. Slow wave sleep rhythms have both thalamic and cortical components. An anterior dominance of EEG spectral power in the delta EEG spectral power range has been reported. A frontal predominance for the increase in delta power following sleep loss has been also reported. This region of the cortex also plays a prominent role in waking executive functions which are preferentially impaired following sleep deprivation. These sleep deprivation induced cognitive impairments have been related to declines in frontal metabolism after sleep loss. While cerebral metabolism declines globally from waking to NREM sleep, these declines are most pronounced in heteromodal association cortex, including the prefrontal cortex.
Insomnia is associated with global cerebral hypermetabolism. Nofzinger et al. (Am J Psychiatry, 2004) assessed regional cerebral glucose metabolism during both waking and NREM sleep in insomnia patients and healthy subjects using [18F] fluoro-2-deoxy-D-glucose positron emission tomography (PET). Insomnia patients show increased global cerebral glucose metabolism during sleep and wakefulness; and a smaller decline in relative metabolism from wakefulness to sleep in wake-promoting regions of the brain. In a comparison between insomnia and depressed patients, insomnia patients demonstrated increased waking relative metabolism in the prefrontal cortex. Finally, recent research has shown that the amount of wakefulness after sleep onset, or WASO, in insomnia patients correlates with increasing metabolism in the prefrontal cortex during NREM sleep.
The relationship between body temperature and quality of sleep generally has been described in connection with prior research in the field of sleep medicine. Heat loss, via selective vasodilatation of distal skin regions (measured by the distal minus proximal skin temperature gradient (DPG), seems to be a crucial process for the circadian regulation of core body temperature (CBT) and sleepiness (Aschoff 1956; Krauchi and Wirz-Justice 1994, 2002; Krauchi et al. 1998, 2000). Increased DPG before lights off has been noted to promote a rapid onset of sleep, suggesting a link between thermoregulatory and arousal (sleepiness) systems (Krauchi et al. 1999, 2000). Hot environments impair the sleep process including falling asleep and maintaining sleep as well as generating slow wave sleep as the increased ambient temperature interferes with the normal declines in core body temperature associated with the sleep onset process. Finally, rapid and intense temperature drops around the sleep onset or sleeping periods are expected to have an arousing effect (Horne and Reyner 1999; Hayashi et al. 2003). In contrast, the apparatuses and methods described herein minimize such adverse effects from temperature changes through application of a controlled (including relatively constant) thermal regulation over a prolonged period of time to a localized surface of the scalp. Thus, it has been found that noninvasive, regional thermal stimulus to the scalp (e.g., between 10 degrees C. and 40 degrees C.) of the head may help adjust metabolism in the cerebral cortex underlying the stimulus and, thereby, provide treatment for neurological disorders.
Previously described technologies for brain temperature regulation (e.g., cooling) may use a cooling apparatus configured to be placed over the scalp/head immediately atop the frontal cortex region, and cooling of the apparatus is typically applied by circulating coolant, although other cooling mechanisms are discussed. Described herein are advancements and further refinements of this early work, expanding the types of thermal regulation apparatuses that may be used, as well as ways for securing the apparatus to the proper region of a patient's head.